Electronic devices, such as conventional mobile phones, comprise, as discrete components, an input unit (e.g. a keypad) for inputting text and a display unit (e.g. an LCD) for displaying the input text. However, the recent miniaturization of electronic devices and advances in display modules (touch screens) have given birth to a new usage of touch screens in which a touch screen serves as either an output window or input window having a keypad implemented on the touch screen as needed, thus freeing the device from requiring a separate discrete input keypad.
A touch screen serving as either an input window or output window has a downside in that a user cannot see the output or other screen displays while entering characters. Therefore, other methods have been introduced, such as that of dividing the screen into several sections and displaying an input window and an output window at the same time according to the user's settings and that of displaying an input window (e.g. a virtual keypad) on the whole touch screen in such a way that the input window is overlapped in a translucent manner over other screen displays including outputs. However, the former method has a problem in that each window becomes too narrow, and the latter method has an issue in that the content of the keypad is not easily seen and confusion with the output displayed on the screen simultaneously may occur and cause inconvenience for the user.
To solve these problems, a new approach has been developed: displaying an input window in a translucent manner in such a way that the transparency of a frequently used key is gradually increased by memorizing the frequency of use for each key, thereby allowing a user to remember the positions of the keys (Refer to Patent Application No. 10-2009-0015523). However, this method has its limitations in that the user must remember the position of the keys on the keypad, and has a downside in that it often increases the frequency of typographical errors. In addition, the configuration of a keypad depends on the type of a terminal and the method cannot be easily applied to the use of Latin-based text or special characters, excluding Korean Hangul.
Therefore the inventors have developed a method of displaying a keypad in such a way that input and output windows are available as wide as possible and at the same time the confusion resulting from the overlapping of the windows is reduced, without requiring a user to memorize the position of each key.